Seventy percent of the world's known oil reserves are non-conventional including heavy oil, extra heavy oil, and bitumen. These oils' high viscosities present a challenge in transporting them through pipelines. Traditionally, producers have used large quantities of condensate as a diluent to reduce the viscosity and make these oils more pumpable. The condensate is typically evaporated and pumped back to the production site via separate pipelines. With rising oil and gas prices, these condensates have become very expensive and their availability has become limited. The energy required to evaporate the condensate from the heavy oil and for its transmission back to the production site has also become increasingly expensive. Thus, there is a significant economic incentive to find methods and compositions to improve the efficiency of transmitting heavy oils via pipelines.
Drag reducers are well known to be added to crude oil being transported through pipelines to reduce the drag of the oil being pumped therethrough to enhance throughput, reduce pressure drop, reduce the power requirements and thus the cost of operating the pipelines. These materials can take various forms, including certain polymers in oil soluble suspensions, emulsions, pellets, gels, microfine powders and particulate slurries. High molecular weight polymers to reduce the friction pressure loss in pipelines are used in a wide variety of applications. Different families of pipeline drag reducers have been developed for optimal performance in different fluid types and under various pipeline conditions. Very high molecular weight polyalpha-olefins are often used as drag reducers for crude oils. However, polyalpha-olefins are subject to shear degradation as the drag reducer and the oil are pumped through successive pumping stations, and thus tend to lose their effectiveness over time and distance. They (i.e. high molecular weight polyalpha-olefin drag reducers) are also used in pipelines with turbulent flow only.
It would be desirable if new methods and compositions for improving flow of heavy oils, such as heavy crude oils and bitumens, for instance by reducing power consumption and pressure drop, particularly if an additive could be used that is not shear degraded over time and distance, or is degraded to a lesser extent than more conventional polyalpha-olefins. Further, it would be desirable to discover new compositions and methods that may be used in all flow regimes—laminar, transition to turbulence, and turbulent flow regimes.